Something that should be factored into our analysis of his scoring prowess is the role that he's determined to play under Gasparini at Atalanta. Since they're a direct team they often have Hojlund running channels on both sides of the box. This leads to him finding himself isolated quite often in transition, which impacts how often he finds himself in central locations are key moments and also accounts for increases of loss of ball retention. So, we can't simply just transplant Hojlund in Atalanta's system into playing under ten Hag, and assume that this says something about Hojlund as a threat. There's every chance that since he will play a different role in ETH's system than under Gasparini, that the tactical difference will put him in the right places at the right time to score more goals.
It's not enough to state that since Serie A is a weaker league, that it's a given that he'll struggle more in the stronger Premier League. This kind of correlation is too myopic and doesn't account for roles influencing greater or poorer performances, nor does it account for the benefits of playing alongside better players who create more high-quality chances.
Eth knows how he wants his CF to operate. Eth understands Hojlund's qualities and how they relate to the profile he wants.